Upper-Limb Muscle Actions & Innervations

Vocabulary flashcards summarizing action, innervation, origin, and insertion for key scapular, shoulder, forearm, wrist, and hand muscles.

Upper Trapezius

Action: Elevates & upwardly rotates scapula.

Innervation: Accessory n. (CN XI), C3-C4.

Origin: External occipital protuberance, nuchal ligament, C1-C7 SPs.

Insertion: Lateral clavicle & acromion.

Middle Trapezius

Action: Retracts scapula.

Innervation: Accessory n. (CN XI), C3-C4.

Origin: C7-T3 SPs.

Insertion: Spine of scapula.

Lower Trapezius

Action: Depresses & upwardly rotates scapula.

Innervation: Accessory n. (CN XI), C3-C4.

Origin: T4-T12 SPs.

Insertion: Spine of scapula.

Levator Scapulae

Action: Elevates & downwardly rotates scapula.

Innervation: Dorsal scapular n. (C5), C3-C4.

Origin: C1-C4 TPs.

Insertion: Superior angle of scapula.

Rhomboid Major

Action: Retracts & downwardly rotates scapula.

Innervation: Dorsal scapular n. (C4-C5).

Origin: T2-T5 SPs.

Insertion: Medial border of scapula (below spine).

Rhomboid Minor

Action: Retracts & downwardly rotates scapula.

Innervation: Dorsal scapular n. (C4-C5).

Origin: C7-T1 SPs.

Insertion: Medial border of scapula (at spine).

Serratus Anterior

Action: Protracts & upwardly rotates scapula.

Innervation: Long thoracic n. (C5-C7).

Origin: Ribs 1-8.

Insertion: Anterior medial border of scapula.

Pectoralis Minor

Action: Depresses, protracts & downwardly rotates scapula. Innervation: Medial pectoral n. (C8-T1).

Origin: Ribs 3-5.

Insertion: Coracoid process.

Deltoid (Anterior)

Action: Flexes & medially rotates shoulder.

Innervation: Axillary n. (C5-C6).

Origin: Lateral clavicle.

Insertion: Deltoid tuberosity.

Deltoid (Middle)

Action: Abducts shoulder.

Innervation: Axillary n. (C5-C6).

Origin: Acromion.

Insertion: Deltoid tuberosity.

Deltoid (Posterior)

Action: Extends & laterally rotates shoulder.

Innervation: Axillary n. (C5-C6).

Origin: Spine of scapula.

Insertion: Deltoid tuberosity.

Supraspinatus

Action: Initiates shoulder abduction.

Innervation: Suprascapular n. (C5-C6).

Origin: Supraspinous fossa.

Insertion: Greater tubercle (humerus).

Infraspinatus

Action: Laterally rotates shoulder.

Innervation: Suprascapular n. (C5-C6).

Origin: Infraspinous fossa.

Insertion: Greater tubercle.

Teres Minor

Action: Laterally rotates & adducts shoulder.

Innervation: Axillary n. (C5-C6).

Origin: Lateral border of scapula.

Insertion: Greater tubercle.

Subscapularis

Action: Medially rotates shoulder.

Innervation: Upper & lower subscapular n. (C5-C6).

Origin: Subscapular fossa.

Insertion: Lesser tubercle.

Pectoralis Major

Action: Adducts, flexes & medially rotates shoulder.

Innervation: Medial & lateral pectoral nn. (C5-T1).

Origin: Medial clavicle, sternum, ribs 1-6.

Insertion: Lateral lip of intertubercular sulcus.

Latissimus Dorsi

Action: Extends, adducts & medially rotates shoulder.

Innervation: Thoracodorsal n. (C6-C8).

Origin: T7-L5 SPs, iliac crest, lower ribs.

Insertion: Floor of intertubercular sulcus.

Coracobrachialis

Action: Flexes & adducts shoulder.

Innervation: Musculocutaneous n. (C5-C7).

Origin: Coracoid process.

Insertion: Medial humeral shaft.

Biceps Brachii (Long Head)

Action: Elbow flexion, forearm supination, weak shoulder flexion. Innervation: Musculocutaneous n. (C5-C6).

Origin: Supraglenoid tubercle.

Insertion: Radial tuberosity & bicipital aponeurosis.

Biceps Brachii (Short Head)

Action: Elbow flexion, forearm supination, weak shoulder flexion. Innervation: Musculocutaneous n. (C5-C6).

Origin: Coracoid process.

Insertion: Radial tuberosity & bicipital aponeurosis.

Triceps Brachii (Long Head)

Action: Extends elbow; extends & adducts shoulder.

Innervation: Radial n. (C6-C8).

Origin: Infraglenoid tubercle.

Insertion: Olecranon.

Triceps Brachii (Lateral Head)

Action: Extends elbow.

Innervation: Radial n. (C6-C8).

Origin: Posterior humerus (above radial groove).

Insertion: Olecranon.

Triceps Brachii (Medial Head)

Action: Extends elbow. Innervation:

Radial n. (C6-C8).

Origin: Posterior humerus (below radial groove).

Insertion: Olecranon.

Pronator Teres

Action: Pronates forearm; assists elbow flexion.

Innervation: Median n. (C6-C7).

Origin: Medial epicondyle & coronoid process.

Insertion: Mid-radius.

Pronator Quadratus

Action: Pronates forearm.

Innervation: Median n. (anterior interosseous, C8-T1).

Origin: Distal anterior ulna.

Insertion: Distal anterior radius.

Supinator

Action: Supinates forearm.

Innervation: Radial n. (deep branch, C6).

Origin: Lateral epicondyle & supinator crest.

Insertion: Proximal lateral radius.

Flexor Carpi Radialis

Action: Flexes & radially deviates wrist.

Innervation: Median n. (C6-C7).

Origin: Medial epicondyle.

Insertion: Bases of 2nd-3rd MCs.

Flexor Carpi Ulnaris

Action: Flexes & ulnarly deviates wrist.

Innervation: Ulnar n. (C7-C8).

Origin: Medial epicondyle & olecranon.

Insertion: Pisiform, hook of hamate, base 5th MC.

Palmaris Longus

Action: Wrist flexion; tenses palmar aponeurosis.

Innervation: Median n. (C7-C8).

Origin: Medial epicondyle.

Insertion: Palmar aponeurosis & flexor retinaculum.

Extensor Carpi Radialis Longus

Action: Extends & radially deviates wrist.

Innervation: Radial n. (C6-C7).

Origin: Lateral supracondylar ridge.

Insertion: Base of 2nd MC.

Extensor Carpi Radialis Brevis

Action: Extends & radially deviates wrist.

Innervation: Radial n. (post. interosseous, C7-C8).

Origin: Lateral epicondyle.

Insertion: Base of 3rd MC.

Extensor Carpi Ulnaris

Action: Extends & ulnarly deviates wrist.

Innervation: Radial n. (post. interosseous, C7-C8).

Origin: Lateral epicondyle & posterior ulna.

Insertion: Base of 5th MC.

Flexor Digitorum Superficialis

Action: Flexes PIP & MCP of fingers 2-5; assists wrist flexion. Innervation: Median n. (C7-T1).

Origin: Medial epicondyle, coronoid, radius.

Insertion: Middle phalanges 2-5.

Flexor Digitorum Profundus

Action: Flexes DIP, PIP & MCP of fingers 2-5; assists wrist flexion. Innervation: Median n. (lateral half) & Ulnar n. (medial half) (C8-T1). Origin: Proximal ulna & interosseous membrane.

Insertion: Distal phalanges 2-5.

Flexor Pollicis Longus

Action: Flexes thumb IP; assists wrist flexion.

Innervation: Median n. (anterior interosseous, C8-T1).

Origin: Anterior radius & interosseous membrane.

Insertion: Distal phalanx of thumb.

Extensor Digitorum

Action: Extends MCP, PIP & DIP of fingers 2-5; assists wrist extension.

Innervation: Radial n. (post. interosseous, C7-C8).

Origin: Lateral epicondyle.

Insertion: Extensor expansions 2-5.

Extensor Indicis

Action: Extends index finger.

Innervation: Radial n. (post. interosseous, C7-C8). 4Origin: Posterior ulna & interosseous membrane.

Insertion: Extensor expansion of index.

Extensor Digiti Minimi

Action: Extends 5th finger.

Innervation: Radial n. (post. interosseous, C7-C8).

Origin: Lateral epicondyle.

Insertion: Extensor expansion of 5th finger.

Abductor Pollicis Brevis

Action: Abducts thumb.

Innervation: Median n. (C8-T1).

Origin: Flexor retinaculum, scaphoid, trapezium.

Insertion: Lateral base of proximal phalanx of thumb.

Flexor Pollicis Brevis

Action: Flexes thumb MCP.

Innervation: Median n. (superficial) & Ulnar n. (deep) (C8-T1). Origin: Flexor retinaculum & trapezium.

Insertion: Lateral base of proximal phalanx of thumb.

Opponens Pollicis

Action: Opposes thumb at CMC.

Innervation: Median n. (C8-T1).

Origin: Flexor retinaculum & trapezium.

Insertion: Lateral 1st metacarpal.

Abductor Digiti Minimi

Action: Abducts 5th finger.

Innervation: Ulnar n. (C8-T1).

Origin: Pisiform.

Insertion: Medial base of proximal phalanx of 5th finger.

Flexor Digiti Minimi Brevis

Action: Flexes 5th finger MCP.

Innervation: Ulnar n. (C8-T1).

Origin: Hook of hamate & flexor retinaculum.

Insertion: Medial base of proximal phalanx of 5th finger.

Opponens Digiti Minimi

Action: Opposes 5th finger at CMC.

Innervation: Ulnar n. (C8-T1).

Origin: Hook of hamate & flexor retinaculum.

Insertion: Medial border of 5th metacarpal.

Lumbricals (1st & 2nd)

Action: Flex MCP & extend IP of fingers 2-3.

Innervation: Median n. (C8-T1).

Origin: Lateral FDP tendons.

Insertion: Extensor expansions 2-3.

Lumbricals (3rd & 4th)

Action: Flex MCP & extend IP of fingers 4-5.

Innervation: Ulnar n. (C8-T1).

Origin: Medial FDP tendons.

Insertion: Extensor expansions 4-5.

Dorsal Interossei (4)

Action: Abduct fingers (DAB).

Innervation: Ulnar n. (C8-T1).

Origin: Adjacent sides of metacarpals.

Insertion: Bases of proximal phalanges & extensor expansions 2-4.

Palmar Interossei (3)

Action: Adduct fingers (PAD).

Innervation: Ulnar n. (C8-T1).

Origin: Palmar metacarpals 2,4,5.

Insertion: Bases of proximal phalanges & extensor expansions 2,4,5.